Signaling means for telephone systems.



F. S. DAVENPORT.

SIGNALING MEANS FOR TELEPHONE SYSTEMS.

APPLICATION FILED APR.30,1907.

Patented June 1, 1909.

2E Fizz 1761767660]? I interru -FREDERICK S. DAVENPORT, OF ATLANTA, GEORGIA.

SIGNALING MEANS FOR TELEPHONE SYSTEMS.

Specification of Letters Patent.

Patented June 1, 1909.

Application filed April 30, 1907. Serial No. 371,113.

To all whom it may concern:

Be it known that I, FREDERICK S. DAVEN- PORT, a citizen of the United States, residing at Atlanta, in the county of Fulton and State of Georgia, have invented certain new and useful Improvements in Signaling Means for Telephone Systems, of which the following is a specification, reference being had therein to the accompanying drawing.

. My inventionrelates to signaling means in a common battery private line telephone system and it consists in the arrangements and combinations herein described.

It is a fact well known by those who have had any connection with central energy systems that the charge and discharge of the condenser in the bell circuit of the subscriber's instrument will cause the bell to give a single tap whenever the receiver is removed from the hookor re laced thereon. This is due to the action of t e momentary current passing through the bell when the condenser is discharged or charged by the making or breakin of the circuit at the hook switch. I have taien advantage of this fact to arrange a system of private lines .feeding from a common battery with devices for ringing the signal bells of the several lines without the necessity that purpose.

This device consists of aninterrupter conveniently located near each subscribers instrument, bridging the line wires and adapted to short circuit the latter intermittently as the interrupter is operated. The intermittent short circuiting of the line wires of course short circuits the condenser which discharges through the bell causing a single tap, while the breaking of the line circuit puts thebattery again on the condenser, char ing the latter and causing another tap of the ell. The .rapid repetition of the charging and discharging of the condenser by means of the ter, will give a prolonged ringing of the bel amply sufficient to serve for signalin purposes. I

' y invention is illustrated in the accompanying drawings in which Figure 1 is a diagrammatic View showing my lnvention as applied to a private line of employing ordinary generators for telephone system. Fig. 2 is a plan View of the interrupter. Fig. 3 is a sectional view taken on the line A-A of Fi 2, looking in the direction of the arrows. ig. 4 is a detail view of the slotted endof the shaft and of the brass contact pieces.

Referring to Fig. 1, 1 and 2 represent the line wires of a private line system. A common feed battery 3 furnishes current for talking and also for ringing the signal bells. Between the terminals of the battery 3 and the corresponding line wires are the impedance coils 4 and 4. The signal bells 5 and 5 of the subscribers instruments bridge the line wires 1 and 2, and the condensers 6 and 6 are arranged in series with the bells in the ordinary manner. In series with the primary windings of the induction coils 7 and 7' are the transmitters 8 and 8 which are connected with the line wires 1, while hook switches 9 and 9 serve to close the circuits through the transmitters. Receivers 10 and 10 are connected to the terminals of the secondary windings of the induction coils 7 and 7. Bridging the line wires 1 and 2 at the oints 11, 11 and 12, 12, are the interrupters and B arranged to short circuit the line wires 1 and 2 and by charging and dischargtnglthe condensers 6 and 6 to ring the signal The construction of the interrupters is as follows: Ablock of wood 13,having a central bore 14 extending part way therethrough is provided with lateral slots 15 and 16, the slot 15 being in the up or face of said block and the slot 16 exten ing midway between the upper and lower surfaces thereof. Secured in the slot 15 is a s ring member 17. A steel shaft 18 is 'ourna ed 1n the slot 16 and its outer end is cut to form a crank. The inner end of the shaft 18 is provided withtwo intersecting slots 19 and 20 (see Fig. 4) adaptedto receive brass contact pieces 21 and 22. The latter are slotted at 21 and 22 and are interjoined as shown in the figure. A second spring contact member 23 is secured at 24 and is adapted to bear on the end of the shaft 18 when the latter is operated. A bearing 25 is provided for the innerend of the shaft 18, said bearlng bemg secured at the bottom of device which admirably the bore. A coiled spring 26 surrounds the shaft 18 and bears at one end on a washer 27 and at the other end on the bearing 25. The spring 23 is normally out of contact with the shaft end.

The spring member 17 is so arranged that the brass contact pieces engage it intermittently and as the shaft is rotated and one contact piece passes from under the spring, the latter is momentarily free from any connection with the contact pieces or with the shaft, until the succeeding contact piece engages it. The springs 23 and 17 are in electrical connection with the line wires 1 and 2 as shown in Fig. 1. I

From the above description it will be seen that when the shaft 18 is pressed against the spring 23, against the action of the coiled spring 26 and is rotated by means of the crank, the line wires will be short circuited intermittently and the condensers 6 and 6 will be charged and discharged. This will ring all the bells on the line in the manner heretofore described. Upon cessation of the ringing the spring 26 will force the shaft out of contact with the spring 23 so that if the spring 17 should happen to-be resting on one of the contact pieces the line will not be permanently short circuited.

I prefer to use a circular block when the interrupter is to be used in connection with a desk instrument. The device can be secured to the bottom of the desk stand in place of the bottom piece ordinarily provided, by means of screws passing through the countersunk screw holes 28. For wall instruments I use a square block and screw it to the back board above the transmitter arm. I

The advantages of my invention will be at once apparent. The interrupter is a simple erforms all the functions of the more comp icated generator. It is easily attached and takes up httle room and its use in a private line system permits the employment of the common feeding battery for ringing as well as for talking urposes. Its utility has been practically emonstrated and its employment for operating signal bells in the manner above described has met with entire success.

It should be observed that I am not limited to the specific form of interrupter herein shown, and may introduce multiplying gearing between the crank and the shaft as in the well known magneto hand enerator, so as to roduce impulses at any esired fre uency. Iany other non-essential changes wil be obvious from the description and drawing, and are clearly within the scope of my invention and of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In a telephone system, a line circuit, a plurality of signaling devices connected thereto, a common source supplying continuous current to the circuit, an inductive device associated with each signalingdevice, and means separate and apart from the signaling devices for charging and discharging said inductive devices from said source so as to actuate the signal devices.

2. In a central energy telephone system, a pair of line wires, a common battery bridged across said line wires, subscribers signal bells bridged across said line wires, condensers in serieswith said signal bells, and manually operated means to intermittently short circuit said line wires to charge and discharge said condensers and thereby ring the signal bells.

3. In a central energy telephone system, a pair of line wires, a common feed battery bridged across-said line wires, subscribers signal bells bridged across said line wires, condensers in series with said signal bells, and an interrupter adapted to intermittently short circuit said line wires to charge and discharge said condensers, and thereby ring the signal bells, said interrupter comprising a base, a shaft journaled in said base having a crank at one end and provided with spaced contact pieces at the other end, a contact spring connected with one line wire and arranged to bear on the shaft, and a second contact spring connected with the other line wire and adapted to bear on said contact pieces.

4. In an electrical signaling system, a line circuit, a source of current connected thereto, signaling-devices connected to said line circuit, condensers in series therewith, and an actuating device or interrupter for the signals associated with the line, and comprising a base, an adjustable shaft journaled therein and provided with intersecting slots, metal contact pieces disposed in said slots and rojecting beyond the perimeter of said shaft, a spring member adapted to engage said contact pieces intermittently when the shaft is rotated, a second spring adapted to engage the ends of said contact pieces in the adjusted position of the shaft, and means operating to keep the latter normally out of engagement with said second spring.

5. In an electric signaling system, a line circuit, a source of current connected thereto, signaling devices connected to said line circuit, condensers'in series therewith, and an actuating device or interrupter for the signals associated with the line, and coin rising a block having a bore extending part f there through, an adjustable shaft journa ed in a slot in said block, one end of said shaft carrying a crank for rotating the same, and the otherlend extending within said bore and having intersecting cuts, metal contact pieces disposed in said cuts, a spring member semally out of engagement with said second 10 cured in a second slot in said block and spring.

adapted to engage said contact pieces inter- In testimony whereof I afiix my signature mittently when the shaft is rotated, a second in presence of two witnesses. spring secured to said block within said bore and adapted to engage the ends of said con- FREDERICK DAVENPORT tact pieces in the adjusted position of the Witnesses: shaft, and a coiled spring attached to said A. L. MILLER,

shaft and operating to keep the latter nor- A. B. TUMLIN. 

